Short descriptions of the parts of the kidney
labelled above:

Renal hilus:

The renal hilus is an indentation near
to the centre of the concave area of the kidney. This
is the area of the kidney through which the ureter leaves
the kidney and the other structures including blood vessels
(illustrated), lymphatic vessels, and nerves enter/leave
the kidney.

Renal capsule:

The renal capsule is a smooth, transparent, fibrous
membrane that surrounds, encloses, and protects
the kidney. Each kidney has it's own renal
capsule (outer layer), which helps to maintain
the shape of the kidney as well as protecting
it from damage.
The renal capsule is itself surrounded by a mass of fatty
tissue that also helps to protect the kidney by damage
by cushioning it in cases of impact or sudden movement.

Renal cortex:

The renal cortex is the outer part of the kidney and
has a reddish colour (shown as very pale brown above).
It has a smooth texture and is the location of the Bowman's
Capsules and the glomeruli, in addition to the proximal
and distal convoluted tubules and their associated blood
supplies (these structures are part of the kidney
nephrons - described in further detail on the page about
kidney
nephrons).

Renal medulla:

The renal medulla is the inner part of the kidney.
"Medulla" means "inner portion". This area is a striated
(striped) red-brown colour.

Renal pyramids:

There are approx. 5 - 18 striated triangular structures
called "Renal Pyramids" within the renal medulla of each
kidney. The apperance of striations is due to many straight
tubules and blood vessels within the renal pyramids.

Renal pelvis:

The renal pelvis is the funnel-shaped basin (cavity)
that receives the urine drained from the kidney nephrons
via the collecting ducts and then the (larger) papillary
ducts..

Renal
artery:

The renal artery delivers oxygenated blood to the kidney.
This main artery divides into many smaller branches as
it enters the kidney via the renal hilus. These smaller
arteries divide into vessels such as the segmental artery,
the interlobar artery, the arcuate artery and the interlobular
artery. These eventually seperate into afferent arterioles,
one of which serves each nephron in the kidney.

Renal
vein:

The renal vein receives deoxygenated blood from
the peritubular veins within the kidney. These merge
into the interlobular, arcuate, interlobar and segmental
veins, which, in turn, deliver deoxygenated blood to
the renal vein, through which it is returned to the systemic
blood circulation system.

Interlobular
artery:

The interlobular artery delivers oxygenated blood
at high pressure to the glomerular capillaries.

Interlobular
vein:

The interlobular vein receives deoxygenated blood
(at lower pressure) that it drains away from the glomerular
filteration units and from the Loops of Henle.

Kidney nephron:

Kidney nephrons are the functional units of the kidneys.
That this, it is the kidney nephrons that actually perform
the kidney's main functions. There are approx. a million
nephrons within each kidney. To find out more about these,
visit the page about Kidney
Nephrons.

Collecting Duct (Kidney):

The collecting duct labelled in the diagram above
is part of the kidney nephron (shown much enlarged).
The distal convoluted tubules* (term explain on the
page about kidney
nephrons) of many nephrons empty
into a single collecting duct. Many such collecting ducts
unite to drain urine extracted by the kidney into papillary
ducts, then into a minor calyx, then the major calyx
(at the centre of the kidney), and finally into the ureter
through which the urine leaves the kidney en-route to
the urinary bladder.

Ureter:

The ureter is the structure through which urine is
conveyed from the kidney to the urinary
bladder.